Analysis implement with opening in insulation film

ABSTRACT

The present invention relates to an analytical tool (X) which includes a substrate ( 1 ), a flow path for moving a sample along the substrate ( 1 ), a reagent portion ( 14 ) provided in the flow path, and an insulating film ( 13 ) covering the substrate ( 1 ) and including an opening ( 15   a ) for defining a region for forming the reagent portion ( 14 ). The insulating film ( 13 ) further includes at least one additional opening ( 15   b ) positioned in a longitudinal direction (N 1 ) relative to the opening ( 15   a ). For instance, the flow path is configured to move the sample by capillary force.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. Ser. No. 10/560,015, filedDec. 8, 2005 entitled ANALYSIS IMPLEMENT WITH OPENING IN INSULATION FILMwhich is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to an analytical tool used for analyzing aparticular component (such as glucose, cholesterol or lactic acid)contained in a sample (e.g. biochemical sample such as blood or urine).

BACKGROUND ART

To measure a glucose level in blood, a method which utilizes adisposable biosensor is often employed as an easy method of measurement(See Patent Document 1, for example). Like the glucose sensor 9 shown inFIGS. 9 and 10 of the present application, there exists a glucose sensorconfigured to measure the response current necessary for the computationof a blood glucose level by using a working electrode 90 and a counterelectrode 91. In the glucose sensor 9, blood is moved by a capillaryforce generated in the capillary 92, and the amount of electron transferupon the reaction between blood and a reagent is measured as theresponse current. As shown in FIGS. 10 and 11, the reagent is retainedas a reagent portion 95 in an opening 94 of an insulating film 93 on asubstrate 96. The reagent portion 95 is formed to be highly soluble sothat the reagent is dispersed in blood when blood is introduced. Asshown in FIGS. 9 and 10, the capillary 92 is defined by stacking a cover98 to the substrate 96 via a spacer 97 formed with a slit 97 a.

The speed of movement of blood (suction force acting on blood) in thecapillary 98 depends on the wettability of a surface of the cover 98 andthe solubility of the reagent portion 95. Generally, the wettability ofthe cover 98 and the solubility of the reagent portion 95 deterioratewith time or depending on the temperature. As better shown in FIG. 10,on the surface of the substrate 96, a stepped portion 99 is formed dueto the provision of the opening 94 in the insulating film 93. Therefore,as shown in FIGS. 12A and 12B, the blood B introduced into the capillary92 may be stopped at the stepped portion 99 in moving the capillary 92.Such a phenomenon is more likely to occur as the suction force in thecapillary 92 deteriorates, i.e., as the wettability of the cover 98 andthe solubility of the reagent portion 95 deteriorate.

The blood B which has stopped moving at the stepped portion 99 may stopits progress in that state. In some cases, however, the blood B movesagain gradually and then suddenly moves largely. When the blood B movesagain, the amount (concentration) of electron mediator existing aroundthe working electrode 90 and the counter electrode 91 suddenly changes.In such a case, as indicated by phantom lines in FIG. 13, the measuredresponse current suddenly increases. The phenomenon that the blood Bmoves again does not necessarily occur at each time of blood glucoselevel measurement, and the timing at which the blood movement phenomenonoccurs is not constant in glucose sensors 9. Therefore, the glucosesensor 9 in which the blood B may move again has poor reproducibility ofcurrent measurements, and hence has poor reproducibility of bloodglucose levels obtained by computation.

Patent Document 1: JP-A 8-10208

DISCLOSURE OF THE INVENTION

An object of the present invention is to provide an analytical tool witha flow path for moving a sample, which is capable of stably supplyingthe sample for a long period of time and enhancing the reproducibilityof sample analysis.

An analytical tool provided according to the present invention comprisesa substrate, a flow path for moving a sample along the substrate, areagent portion provided in the flow path, and an insulating filmcovering the substrate and including an opening for defining a regionfor forming the reagent portion. The insulating film further includes atleast one additional opening positioned downstream from the opening in amovement direction in which the sample moves.

For instance, the flow path is configured to move the sample bycapillary force.

For instance, the analytical tool of the present invention may beadapted to use a biochemical sample (such as blood, urine or saliva) asthe sample.

The analytical tool of the present invention may further comprise afirst and a second electrodes provided at the substrate. In this case,the insulating film covers the first and the second electrodes, withpart of the first and the second electrodes exposed.

For instance, at least one additional opening is connected to theopening. In this case, the insulating film includes a control edgedefining a downstream edge of the region for forming the reagent portionin the movement direction.

For instance, at least one additional opening is connected to theopening at a portion of the control edge adjoining in a direction whichis perpendicular to the movement direction.

The control edge may be in the form of a straight line extending in adirection which is perpendicular to the movement direction. In thiscase, the dimension of the control edge in the perpendicular directionis set to 60 to 95% of the dimension of the opening in the perpendiculardirection. The control edge may be in the form of a curved line dentedtoward a downstream side in the movement direction.

For instance, the insulating film includes an island portion which is inthe form of an island and which includes the control edge. The islandportion may have a width which decreases as the island portion extendsdownstream in the movement direction. The configuration of the islandportion may be triangular or semicircular, for example.

Alternatively, the insulating film may include a peninsula portion whichis in the form of peninsula and which includes the control edge. In thiscase, at least one additional opening includes a pair of additionalopenings arranged to adjoin the peninsula portion in a width direction.Each of the paired openings may have a constant width. Alternatively,each of the paired openings includes a narrow portion positionedrelatively upstream in the movement direction and a wide portionpositioned downstream from the narrow portion.

At least part of at least one additional opening may be offset relativeto the opening in the perpendicular direction.

For instance, the flow path may be formed by stacking a cover to thesubstrate via a spacer. The spacer includes a pair of surfaces definingthe dimension of the flow path in the perpendicular direction and facingeach other while being spaced from each other in the perpendiculardirection. In this case, the spacing between the paired facing surfacesis larger than the dimension of the opening in the perpendiculardirection.

When the flow path is configured to move the sample by capillary force,the cover includes a discharge port for discharging gas from within theflow path. In this case, the downstream end of the opening in themovement direction is positioned upstream from the upstream end of thedischarge port in the movement direction.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an overall perspective view of an example of glucose sensoraccording to the present invention.

FIG. 2 is an exploded perspective view of the glucose sensor shown inFIG. 1

FIG. 3 is a sectional view taken along lines in FIG. 1.

FIG. 4 is a plan view showing an end of the glucose sensor of FIG. 1 ina state in which the cover and the spacer are removed.

FIG. 5 includes plan views corresponding to FIG. 4, showing otherexamples of stopper portion of the glucose sensor.

FIG. 6 includes plan views corresponding to FIG. 4, showing otherexamples of second opening of the glucose sensor.

FIG. 7 includes graphs showing measurements of response current inInventive Example 1.

FIG. 8 includes graphs showing measurements of response current inComparative Example 1.

FIG. 9 is an overall perspective view showing a prior art glucosesensor.

FIG. 10 is a sectional view taken along lines X-X in FIG. 9.

FIG. 11 is a plan view showing an end of the glucose sensor of FIG. 9 ina state in which the cover and the spacer are removed.

FIG. 12 includes views for describing problems of the prior art glucosesensor, and FIG. 12A is a sectional view corresponding to FIG. 10,whereas FIG. 12B is a sectional view corresponding to FIG. 11.

FIG. 13 is a graph showing an example of change of responsive currentwith time, which is measured in the prior art glucose sensor.

BEST MODE FOR CARRYING OUT THE INVENTION

The glucose sensor X shown in FIGS. 1 through 3 is a disposable sensorwhich is mounted, in use, to a concentration measuring apparatus (notshown) to measure a blood glucose level. The glucose sensor X comprisesa substrate 1 having an elongated rectangular configuration, and a cover3 stacked to the substrate via a spacer 2. In the glucose sensor X,these elements 1-3 define a capillary 4 extending in the longitudinaldirection of the substrate 1. The capillary 4 serves to move the bloodintroduced through an introduction port 40 in the longitudinal directionof the substrate 1 (the direction of N1 in figures) by utilizingcapillary action and serves to retain the introduced blood.

The spacer 2 defines the distance from the upper surface 10 of thesubstrate 1 to the lower surface 30 of the cover 3, i.e. the height ofthe capillary 4, and may comprise a double-sided tape, for example. Thespacer 2 includes a slit 20 having an open front end. The slit 20defines the width of the capillary 4, and the open front end of the slit20 provides the introduction port 40 for introducing blood into thecapillary 4. The slit 20 includes a pair of facing surfaces 20 a facingeach other while being spaced from each other in the widthwise direction(N3, N4) of the substrate 1.

The cover 3 includes a through-hole 31. The through-hole 31 is utilizedfor discharging gas from within the capillary 4 to the outside. Thesurface of the cover 3 which faces the capillary 4 is made hydrophilic.Such a cover 3 may be provided by forming the entirety of the cover 3 byusing a material having a high wettability such as vinylon or highcrystallinity PVA or hydrophilically treating the surface of the coverwhich faces the capillary 4. For example, the hydrophilization may beperformed by the irradiation of ultraviolet rays or the application of asurfactant such as lecithin.

As clearly shown in FIGS. 2 and 3, the substrate 1 is made of resin suchas PET. The upper surface 10 of the substrate is formed with a workingelectrode 11, a counter electrode 12, an insulating film 13 and areagent portion 14. Most part of the working electrode 11 and thecounter electrode 12 extend in the longitudinal direction of thesubstrate 1 (the direction of N1, N2 in the figures), but the ends 11 aand 12 a thereof extend in the widthwise direction of the substrate 1(the direction of N3, N4 in the figures). The working electrode 11 andthe counter electrode 12 further include ends 11 b and 12 b constitutingterminals for coming into contact with terminals provided in theconcentration measuring apparatus (not shown). The working electrode 11and the counter electrode 12 may be made by screen printing usingconductive carbon ink.

The insulating film 13 serves to protect the working electrode 11 andthe counter electrode 12 from water and dust, for example. Theinsulating film 13 is made hydrophobic as compared with the surface ofthe substrate 1, the working electrode 11 and the counter electrode 12,and the contact angle at the surfaces is set to 100 to 120 degrees, forexample. Such an insulating film 13 may be provided by applying inkcontaining a water repellent material and then drying, or by curing UVcuring resin containing a water repellent agent. As better shown inFIGS. 2 and 4, the insulating film 13 covers most part of the workingelectrode 11 and counter electrode 12, while leaving the ends 11 a, 12a, 11 b and 12 b of the working electrode 11 and the counter electrode12 exposed. The insulating film 13 includes a first opening 15 a and apair of second openings 15 b.

The first opening 15 a defines a region for forming the reagent portion14 on a portion of the substrate 1 at which the ends 11 a and 12 a ofthe working electrode 11 and the counter electrode 12 are formed. Thefirst opening 15 a has an elongated rectangular configuration extendingin the longitudinal direction of the substrate 1 (the direction of N1,N2 in the figures), and has a width W1 which is smaller than thedistance W2 between the facing surfaces 20 a of the slit 20 of thespacer 2.

The paired second openings 15 b serve to promote the movement of bloodbeyond the first opening 15 a in the capillary 4A. The second openings15 b are rectangular, spaced from each other in the widthwise directionof the substrate 1, and arranged on the N1 direction side of the firstopening 15 a (downstream in the direction of movement of blood in thecapillary 4). Each of the second openings 15 b is connected to the firstopening 15 a and includes a portion which is offset from the firstopening 15 a in the widthwise direction of the substrate 1 (thedirection of N3, N4 in figures). Between the second openings 15 b isprovided a stopper portion 16. The stopper portion 16 comprises part ofthe insulating film 13 and is shaped like a peninsula. The stopperportion 16 includes an edge 16 a at opposite sides of which the secondopenings 15 b are connected to the first opening 15 a. As a result, thedimension of each second opening 15 b in the direction of N3, N4 islarger than the dimension of the connecting portion between the firstopening 15 a and the second opening 15 b in the direction of N3, N4.

As will be described later in detail, in forming the reagent portion 14in the first opening 15 a, the stopper portion 16 serves to prevent thereagent solution to form the reagent portion 14 from spreading more thannecessary in the direction of N1. Specifically, this role issubstantially fulfilled by the control edge 16 a. The control edge 16 adefines the boundary between the first opening 15 a and the stopperportion 16 and is positioned closer to the introduction port 40 (on theN2 direction side) than the edge 31 a of the through-hole 31 of thecover 3 is. For instance, the dimension, i.e., the length of the controledge 16 a is set to 60 to 95% of the dimension of the first opening 15 ain the widthwise direction (the direction of N3, N4 in the figures).When the dimension of the control edge 16 a is unfavorably smaller thanthe dimension of the first opening 15 a in the direction of N3, N4, thespreading of the reagent solution in the direction of N1 cannot besufficiently suppressed, so that the reagent solution flows into thesecond openings 15 b. On the other hand, when the difference between thedimension of the control edge 16 a and that of the first opening 15 a inthe direction of N3, N4 is unfavorably small, the blood introduced intothe capillary 4 cannot be sufficiently moved into the second openings 15b.

The reagent portion 14 is provided in the first opening 15 a of theinsulating film 13 so as to bridge the ends 11 a and 12 a of the workingelectrode 11 and the counter electrode 12. For instance, the reagentportion includes an electron mediator, and a relatively small amount ofoxidoreductase. The reagent portion 14 is in a porous solid state easilysoluble in blood. Therefore, when blood is introduced into the capillary4, blood easily moves along the surface of the substrate 1 due to theaction of the reagent portion 14, and a liquid phase reaction systemincluding the electron mediator, oxidoreductase and glucose isestablished in the capillary 4.

As the oxidoreductase, use may be made of GOD or GDH, and typically,PQQGDH may be used. As the electron mediator, use may be made ofruthenium complexes or iron complexes, and typically [Ru(NH₃)₆]Cl₃ orK₃[Fe(CN)₆] may be used.

For instance, the reagent portion 14 may be formed by dispensing areagent solution containing electron mediator and oxidoreductase intothe opening 15 a and then drying the reagent solution. When a reagentsolution is dispensed into the first opening 15 a, the reagent solutiontries to spread in the first opening 15 a. However, the spreading isstopped at a pair of edges of the first opening 15 a which are oppositein the widthwise direction of the substrate 1 (the direction of N3, N4in the figures) and the edge 16 a of the stopper portion 16. Therefore,the reagent solution can be dispensed selectively into the first opening15 a, and the reagent portion 14 can be formed selectively in the firstopening 15 a.

A method for measuring a glucose level by using the glucose sensor Xwill be described.

With the glucose sensor X, the measurement of a blood glucose level canbe performed automatically by mounting the glucose sensor X to aconcentration measuring apparatus (not shown) and introducing blood intothe capillary 4 through the introduction port 40 of the glucose sensorX.

When the glucose sensor X is mounted to a concentration measuringapparatus (not shown), the working electrode 11 and the counterelectrode 12 of the glucose sensor X come into contact with terminals(not shown) of the concentration measuring apparatus. When blood isintroduced into the capillary 4, the blood moves from the introductionport 40 toward the through-hole 31 due to the capillary action occurringin the capillary 4. As the blood moves, the reagent portion is dissolvedby the blood, whereby a liquid phase reaction system is established inthe capillary 4. By using the working electrode 11 and the counterelectrode 12, a voltage can be applied to the liquid phase reactionsystem or the response current when a voltage is applied can bemeasured.

In the liquid phase reaction system, the oxidoreductase, for example,reacts specifically with glucose in blood to remove electrons fromglucose, and the electrons are supplied to the electron mediator to makethe electron mediator a reduction type. When a voltage is applied to theliquid phase reaction system by using the working electrode 11 and thecounter electrode 12, electrons are supplied from the electron mediator,which has become the reduction type, to the working electrode 11.Therefore, in the concentration measuring apparatus, the amount ofelectrons supplied to the working electrode 11 can be measured as theresponse current. In the concentration measuring apparatus (not shown),the blood glucose level is computed based on the response currentmeasured when a predetermined time has elapsed from the introduction ofblood into the capillary 4.

In the glucose sensor X, the first opening 15 a and the second openings15 b of the insulating film 13 are connected to each other. Therefore,on the surface of the substrate 1 within the capillary 4, the portionwhich is not covered by the insulating film 13, i.e., the portion whichis more hydrophilic than the insulating film 13 extends in the movementdirection N1 of blood. Since blood can positively move through thehydrophilic region in the glucose sensor X, blood positively moves fromthe first opening 15 a toward the second openings 15 b. Moreover, sincethe width of each second opening 15 b is larger than the dimension ofthe connecting portion between the first opening 15 a and the secondopening 15 b, the movement of blood from the first opening 15 a to thesecond opening 15 b is further facilitated. As a result, it is possibleto prevent blood from once stopping at the edge of the first opening 15a, i.e. at the edge 16 a of the stopper portion 16 and then movingagain. Accordingly, the possibility that the amount (concentration) ofthe electron mediator existing around the end 11 a of the workingelectrode 11 suddenly changes is reduced, so that the response currentmeasurement becomes close to the value which should be obtained.Therefore, in the glucose sensor X, the reproducibility of responsecurrent measurement, and hence the reproducibility of the blood glucoselevel obtained by computation can be enhanced. Such an advantageous isobtained when the wettability (hydrophilic property) of the cover 3 orthe solubility of the reagent portion 14 is reduced with time ordepending on the temperature and hence the suction force in thecapillary 4 is deteriorated.

The present invention is not limited to the foregoing embodiment but maybe modified in various ways. For instance, as shown in FIG. 5A, thestopper portion 16B may be in the form of a rectangular island which isseparate from the insulating film 13. In the case where a stopperportion which is separate from the insulating film is provided, theconfiguration may not be rectangular but may be triangular orsemicircular like the stopper portions 16C, 16D shown in FIG. 5B or 5Cor may be configured otherwise. In the example shown in FIG. 5B or 5C,the linear control edge 16Ca, 16Da defines the boundary with the firstopening 15 a, and the dimension of the stopper portion in the widthdirection N3, N4 decreases as the stopper portion extends in thedirection N1 which is the blood movement direction. Therefore, whenblood moves from the first opening 15 a toward the second openings 15 b,the blood is likely to move to the rear side, i.e. N1 side of thestopper portion 16C, 16D. As a result, regardless of the provision ofthe stopper portion 16C, 16D, the blood can properly move to the secondopenings 15 b.

The stopper portion needs to have a configuration which can prevent thereagent solution from flowing into the second openings in forming thereagent portion. Therefore, instead of the above-described linearcontrol edge, the stopper 16E may have a curved control edge dented inthe direction of arrow N1 like the control edge 16Ea of shown in FIG.5D. Although the stopper portion 16E shown in FIG. 5D is in the form ofa peninsula, such a curved control edge is also applicable to a stopperportion in the form of an island separated from the insulating film.

The second opening may be configured as shown in FIGS. 6A-6D.Specifically, in the examples shown in FIGS. 6A and 6B, a single secondopening 15Fb or 15 Gb is provided. In the example shown in FIG. 6C, thesecond openings 15Hb are not offset from the first opening 15 a in thedirection of arrows N3, N4. In the example shown in FIG. 6D, each of thesecond openings 15Ib includes a narrow portion 15Ib′ connected to thefirst opening 15 a and a wide portion 15Ib″ positioned downstream fromthe narrow portion 15Ib′ (on the N1 side) in the blood movementdirection. The second opening may be configured in various ways to havea configuration other than those shown in FIGS. 6A-6D.

The present invention is not limited to a glucose sensor configured tomeasure a glucose level in blood but also applicable to a glucose sensorfor measuring a component in blood other than glucose (such ascholesterol or lactic acid) and also applicable to an analytical toolfor analyzing a sample other than blood (such as urine or saliva), forexample. Further, the present invention is not limited to an analyticaltool which utilizes an electrode method but also applicable to ananalytical tool configured to analyze a particular component in a sampleby an optical method.

EXAMPLES

Hereinafter, it is proved that the glucose sensor according to thepresent invention can enhance the reproducibility of response currentmeasurement and accurately measure a glucose level.

Inventive Example 1

In this Inventive Example, use was made of a glucose sensor having abasic structure similar to that of the glucose sensor X shown in FIGS. 1through 4 and second openings similar to the second openings 15Hb shownin FIG. 6C. Other conditions of the glucose sensor used in this Exampleare as follows.

The substrate 1 was made of PET (Tradename: “E-22” available from TorayIndustries, Inc.) The working electrode 11 and the counter electrode 12were formed to have a thickness of 10 μm by screen printing using carbonink. The insulating film 13 was formed to have a thickness of 20 μm anda contact angle of 105 degrees by screen printing using water repellentresist ink. In the insulating film 13, the first opening 15 a was formedto have a length L1 of 2.5 mm and a width W1 of 1.7 mm (See FIGS. 2 and6C). In this Inventive Example 1, the stopper portion of the glucosesensor was formed to have a width W3 of 0.6 mm (See FIG. 6C). Thereagent portion formed included [Ru(NH₃)₆]Cl₃ (“LM722” available fromDOJINDO LABORATORIES) as electron mediator, and PQQGDH (Tradename:“PQQ-GDH” available from TOYOBO. CO., LTD.) as oxidoreductase. Theelectron mediator and the oxidoreductase were so included thatrespective concentrations upon dissolution due to the filling of thecapillary 4 with blood become 4 vol % and 3 U, respectively. As thespacer 2, use was made of a double-sided tape (Tradename: “550PS5”available from SEKISUI CHEMICAL CO., LTD.). The cover was formed byusing vinylon (Tradename: “vinylon sheet VF-LH” available from TOHCELLOCO., LTD.) The capillary 4 was formed to have a width W2 (See FIGS. 1and 2) of 1.8 mm, a length L2 of 3.2 mm, and a height H2 (See FIG. 3) of45 μm.

In this Inventive Example, the reproducibility was evaluated based onthe time course of response current. The time course of response currentwas measured ten times by using whole blood having a glucose level of400 mg/dL and a Hct of 42%. The application of voltage of 200 mV betweenthe working electrode and the counter electrode was started five secondsafter the start of the blood introduction, and the response current wasmeasured over time, i.e. every 100 msec after the start of the voltageapplication. As the glucose sensor, two kinds of sensors were used, i.e.one immediately after the manufacturing and the other one stored for 30days under the conditions of 50° C. and about 2% relative humidity afterthe manufacturing. FIGS. 7A and 7B show the measurement results of timecourse of the glucose sensor immediately after the manufacturing and theglucose sensor 30 days after the manufacturing, respectively.

Comparative Example 1

In this Comparative Example, the time course of response current wasmeasured in the same way as in Inventive Example 1 except that a glucosesensor which did not include a second opening (FIGS. 9 through 11) wasused. FIGS. 8A and 8B show the measurement results of time course of theglucose sensor immediately after the manufacturing and the glucosesensor 30 days after the manufacturing, respectively.

As will be understood from FIGS. 7A and 8A, with respect to the glucosesensors immediately after the manufacturing, disturbance of the timecourse is not found in both of the glucose sensor of Inventive Example 1and that of Comparative Example 1. However, as will be understood fromFIGS. 7B and 8B, with respect to the glucose sensors stored for 30 days,disturbance of the time course is not found in the glucose sensor ofInventive Example 1, whereas disturbance of the time course is found inthe glucose sensor of Comparative Example 1. This result reveals that,by forming a second opening communicating with the first opening and astopper portion like the glucose sensor of Inventive Example 1, areagent portion can be properly formed in the first opening and thereproducibility of response current measurement can be enhanced.Moreover, the storage of the glucose sensor was performed underunfavorable conditions of 50° C. and about 2% relative humidity. Thisfact reveals that the glucose sensor of Inventive Example 1 can measurethe response current with high reproducibility for a long period oftime. Therefore, it is concluded that the glucose sensor of InventiveExample 1 can accurately measure the response current, and hence,measure the glucose level for a long period of time.

1-16. (canceled)
 17. An analytical tool with opening in insulating film,the tool comprising: a substrate; a flow path for moving a sample alongthe substrate; a reagent portion provided in the flow path; aninsulating film covering the substrate and including a first openingdefining a region for forming the reagent portion and at lest oneadditional opening positioned downstream from the first opening in amovement direction in which the sample moves, said at least oneadditional opening being connected to the first opening; and a stopperportion including a control edge defining a downstream edge of theregion for forming the reagent portion in the movement direction;wherein at least part of said at least one additional opening is offsetrelative to the first opening in a direction which is perpendicular tothe movement direction, and the control edge of the stopper portion isdisposed at a same position as an edge of the first opening.
 18. Theanalytical tool with opening in insulating film according to claim 17,further comprising a spacer and a cover stacked on the substrate toprovide the flow path; wherein the spacer includes a pair of surfacesdefining a dimension of the flow path in a direction which isperpendicular to the movement direction and facing each other whilebeing spaced from each other in the perpendicular direction; and whereinthe spacing between the paired facing surfaces is larger than adimension of the first opening in the perpendicular direction.
 19. Theanalytical tool with opening in insulating film according to claim 18,wherein the flow path is configured to move the sample by capillaryforce.
 20. The analytical tool with opening in insulating film accordingto claim 19, wherein the cover includes a discharge port for discharginggas from within the flow path; and wherein a downstream end of the firstopening in the movement direction is positioned upstream from anupstream end of the discharge port in the movement direction.